A risk analysis is the search for hazards and the estimation of the probabilities and severities of any resulting harm.
When the term risk analysis is used, it often refers to a hazard analysis.
1. Prerequisite for the hazard/risk analysis
To identify the risks, medical device manufacturers must fulfill the following requirements:
- Interdisciplinary risk management team assembled (see 3. c))
- Risk management plan created
- Risk acceptance criteria defined
- Intended purpose and normal use specified
- Safety-relevant characteristics of the device described
2. Methods of hazard/risk analysis
The objective of risk analysis obviously is to identify risks.
Step 1: Identify hazards (hazard analysis)
The first step is to search for hazards based on the intended purpose, the safety-relevant characteristics of the device, and, if applicable, its design.
The hazard analysis procedures are recommended for this purpose:
- PHA (Preliminary Hazard Analysis)
- FMEA (Failure Mode and Effect Analysis)
- Fault Tree Analysis (FTA)
- HAZOP (Hazard Operability)
Step 2: Estimate probabilities and severities of resulting harm
Risks are combinations of the probability of occurrence and the severity of harm. Both must, therefore, be assessed in this step.
Step 3: Decide on the justifiability of the risks
Based on risk acceptance, manufacturers decide on the acceptability of individual risks and, later on, the acceptability of all (residual) risks.
Strictly speaking, this step no longer counts as risk analysis.
3. Tips on risk analysis
a) Consider the specifics of risk analysis for software
Our tips on risk analysis for software have become so extensive that we have dedicated a separate article to them.
b) Be aware that one hazard can lead to several risks
One hazard can lead to several risks, as the following example shows.
Example
If a hospital information system has incorrectly saved a laboratory value as negative instead of positive and the doctor, therefore, administers the wrong medication, a patient may come to harm. The patient may die or “only” suffer from nausea.
Depending on your definition of the harm classes, the first harm (death) could be defined as catastrophic, and the second (nausea) as minor. However, both harms have a different probability.
c) Ensure qualification of the persons involved
ISO 14971 requires that the personnel responsible for risk management have the necessary qualifications.
- Risk manager
- Methods of hazard analysis and risk analysis
- Regulatory requirements for risk management
- Moderation skills, project management skills
- Capability to document risk management (documents, tools)
- Technical experts
- Detailed understanding of system and software architectures
- Knowledge of internal and external interfaces
- Knowledge of components and technologies and their failure modes
- Context experts
- Thorough knowledge of the context of use
- Capability to assess hazardous situations resulting from use errors and system malfunctions
- Doctors and physicians
- Knowledge of the health status of the intended patients
- Capability to determine the severity and probabilities resulting from hazardous situations